Nanoporous Pt and Ru catalysts by chemical dealloying of Pt-Al and Ru-Al alloys for ultrafast hydrogen generation

Abstract

Novel nanoporous catalysts from selective dissolution of alloys have been prepared for fast hydrogen generation from chemical hydrides. Pt and Ru have been used as precious metals in the alloys, while the nonprecious metal is Al. The alloy composition has been arranged by sputtering power of Al, which is varied from 200 to 400 W for Pt-Al and Ru-Al alloys. The influence of particle size on the sputtering power of Al has been demonstrated. The particle size of the Pt nanoparticle decreases from 900 to 90 nm when the sputtering power of Al is increased from 200 to 400 W. However, the particle size of the Ru nanoparticle decreased from 610 to 55 with the same increase in Al sputtering power. The hydrolysis reaction rate of NaBH4 scales with the sputtering power of Al and has been raised from 20 to 90 L min−1gcatalyst−1 for Pt while it increases from 23 to 110 L min−1gcatalyst−1 for Ru. The BET analysis has demonstrated that the measured surface areas of the Pt and Ru nanoparticles are approximately 55.5 and 151 m2 g−1, respectively. Joint like morphology providing the porous structure has been clearly concluded by TEM analysis. The average pore sizes are 1 and 10 nm for the Ru and Pt nanoparticles, respectively. In this study, fast hydrogen generation with lower activation energies of 31.7 and 32.1 kJ mol−1 has been achieved for the Pt and Ru nanoparticles, respectively. The critical parameters demonstrating the high catalytic activity in the hydrolysis reaction of NaBH4 are reported for the catalysts developed by the dealloying process.